Tube coupling

ABSTRACT

A coupling for unflared tubes comprising a body with a nut threadably connected thereto so as to form a chamber therebetween, a deformable gripping and sealing sleeve in the chamber and being undeformed when the nut and body are partially threaded together so that an unflared tube may be inserted into the nut, body and sleeve to a position where it may be gripped and sealed by the sleeve upon deformation of the latter by further threading of the nut upon the body. The nut has mounted therein a ring of flexible spring metal slotted so as to form fingers whose radially inner ends are initially on a diameter smaller than the outside diameter of the tube and bendable by insertion of the tube therethrough while the sleeve is undeformed so as to grip the tube by spring action to prevent withdrawal of the tube, as by gravity, and thus to hold the same in its proper position for being gripped by the deformable sleeve upon final tightening of the nut upon the body.

Background of the Invention

Couplings for flareless tubes, such as shown in U.S. Letters Patent3,499,671, which include a deformable metal sleeve between a nut andbody having threaded engagement with each other, have many uses inindustry. This type of coupling is particularly convenient to usebecause the nut, body and sleeve can be preassembled to a finger-tightposition wherein the sleeve remains undeformed and in which finger-tightcondition the tube may readily inserted through the nut and sleeve andinto the body whereupon the installer need only tighten the nut upon thebody to deform the sleeve into gripping and sealing engagement with thetube.

However, in some installations the fitting body, with the nut and sleevein finger-tight position thereon, must be connected to a housing orpanel prior to installation of the tube and in a vertical position inwhich the nut is lowermost. Now, when the tube is inserted it must beheld in its proper position by the workman until the nut is tightenedupon the coupling body for deforming the sleeve into tight grippingengagement with the tube. It is not always convenient for the workman tohold the tube during tightening of the nut in a manner to prevent thetube from slipping out of the coupling, either completely or partially.

In other cases, such as assembly line production of assembled tubes, thetube may be inserted into the loosely assembled coupling at one stationand the nut tightened at another and the tube may partially withdrawduring handling between the two stations.

In either case, the tube may not be in its proper position for finaltightening of the nut with the result that the tube may not be securelygripped or sealed.

SUMMARY OF THE INVENTION

The present invention overcomes the above problems by providing a secondgripping member in the form of a ring attached to the outer end of thenut and being slotted to form fingers whose radially inner ends areinitially smaller in diameter than the tube outside diameter and whichare bendable by insertion of the tube therethrough. The fingers areinclined so that they will be readily expandable to the outside diameterof the tube upon insertion of the latter but retain a grip upon the tubeby spring action of the fingers. This spring action, plus theinclination of the fingers, is such that the fingers will tend tostraighten out for increasing the security of the grip upon the tubewhen the tube attempts to move in a direction for withdrawing the samefrom the coupling. Thus, when the tube is inserted to its properposition within the coupling for final tightening of the nut upon thebody, the slotted ring will effectively hold the tube in this positionso that the workman can tighten the nut without at the same time holdingthe tube in its proper position.

In this coupling, the deformable sleeve is a heavier member than theslotted ring and provides the main grip upon the tube when the couplingis fully assembled. The slotted ring is mounted within a recess in thenut so as to be permanently retained therein but has slight radial andaxial clearance in the recess so that the nut can rotate relative to theslotted ring when the latter grips the tube. In addition, the slottedring is thin and flexible and bears against the nut only at a locationclose to its outer periphery so that the slotted ring, when the radiallyinner edges of the fingers are in gripping engagement with the tube, maybend between its inner and outer diameters during travel of the nutalong the tube during final tightening of the nut upon the couplingbody.

DETAIL DESCRIPTION

FIG. 1 is a view, partly in cross section, of the coupling with theparts in the finger-tight position and the tube inserted therein.

FIG. 2 is a view like FIG. 1 but showing the coupling parts in the fullytightened condition.

FIG. 3 is an end view of the slotted ring.

FIG. 4 is a side view of the slotted ring and a fragmentary section viewof the nut in its initial condition for receiving the ring.

FIG. 5 is a fragmentary section view showing how the nut retains theslotted ring with slight radial and axial clearance therewith.

The coupling comprises a body 10 having a bore 11 of a size to receive atube 12 with a small clearance therewith. The body has a stop shoulder14 at the inner end of bore 11 and an outwardly flared camming surface15 at the other end. The body also has an external thread 17 forthreadably engaging an internally threaded bore 18 in a nut 19. At theinner end of threaded bore 18 the nut has a tapered shoulder 20 formingone end of a chamber 21 formed between the nut and body 10 when theparts are threaded together and which chamber receives a deformablemetal sleeve 24 whose front end 25 engages flare mouth 15 and whose backend 26 engages nut shoulder 20. The sleeve and nut have bores 28, 29therethrough of approximately the same diameter as body bore 11 so as tohave an initial slight clearance with the outside diameter of tube 12.

As shown in FIG. 3, the back end of nut 19 is initially formed with athin projecting cylindrical portion 31 that forms a recess 32. The innerwall of this recess has a transverse portion 33 that intersects achamfered portion 34 having an angle of approximately 45° with thelongitudinal axis of the nut.

Mounted within recess 32 is a ring 36 of thin flexible spring steel. Ithas a radially outer portion 37 lying in a plane perpendicular to thelongitudinal axis of the ring and a radially inner portion 38 that isinitially at an angle of about 45° to the longitudinal axis. The ringhas circumferentially spaced slots 39 that extend completely throughslanted inner portion 38 and partially into outer portion 37 so as toform flexible fingers 41 whose radially inner ends 42 initially lie in acircle whose diameter is slightly less than the outside diameter of tube12. The thickness of ring 36 is approximately 0.010 inch and thematerial is preferably stainless steel so that the fingers 38 willreadily flex radially outwardly to permit the tube to pass therethroughwhen moved in a direction from left to right with relation to FIG. 3 butwhich have considerable spring tension for maintaining the fingers inengagement with the tube.

Ring 36 is receivable within nut recess 32 as shown in FIG. 3. Lip 31 isthen rolled over in the manner shown in FIG. 1 for retaining the ringupon the nut. Lip 31, when in the rolled-over condition shown in FIG. 1loosely confined ring 36 in both axial and radial directions so thatwhen the ring is in gripping engagement with the tube, nut 19 is freelyrotatable relative to the ring. Also, the rolled-over lip 31 provides arear wall for the recess that radially overlaps ring portion 37 by onlya small amount, such as about 0.020 inch diametrally, but preferably nomore than about one-eighth the initial radial width of the ring betweenits inner and outer margins, so that lip 31 will not interfere withbending of ring portions 37 and fingers 38 when the fingers have grippedthe tube and the nut is advanced along the tube to its final threadedposition upon body 10. Nut chamfer 34 is formed so that it will form asubstantial clearance with fingers 38 and not interfere with flexing ofthe latter radially outwardly when the tube is inserted. In furtheranceof this objective transverse inner wall 35 of recess 32 is of narrowradial width so that it also radially overlaps ring 36 by no more thanabout one-eighth the initial radial width of ring 36.

Mounting of the ring 36 in the nut by spinning or crimping over lip 31is accomplished at the factory where the nut and sleeve is thenassembled to the finger-tight position shown in FIG. 1 prior to shipmentof the coupling assembly to the customer. When the coupling is to beinstalled, the body 10, with the nut and sleeve in the finger-tightposition, is first attached to the housing or other member 16 to which atube is to be connected. The tube 12 is then inserted through ring 36,nut 19 and sleeve 24 into body bore 11 until it seats against bodyshoulder 14. As the tube passes through ring 36, it spreads fingers 38radially outwardly but the spring tension in the fingers causes thefingers to remain in contact with the outer surface of the tube. Ifgravity or some other force is then applied to the tube in a directionto withdraw it from the coupling, fingers 38 dig into the tube and aforce is applied to the fingers tending to swing them toward atransverse plane. This causes the fingers to increase their grip uponthe tube and prevent its withdrawal so that the tube will be held byring 36 in the position shown in FIG. 1 with the inner end of the tubeeither in contact with body shoulder 14 or perhaps spaced a fewthousandths of an inch therefrom.

The nut 19 may then be threaded further onto body 10 to move sleeve 24toward body 10 so that the inner end of the sleeve will be contracted byflare mouth 15 into gripping and sealing engagement with the tube. Uponinitial contact of the forward end of sleeve 24 with the tube the sleevewill move the tube inwardly so as to take up any slight clearance thatmay have existed between the end of the tube and body shoulder 14 andthereafter the sleeve will move relative to the tube as the front endcontracts radially until the sleeve is in its final position.

As nut 19 is threaded toward its final position on body 10, sleeve 36will be moved forwardly with it. During such movement, fingers 38 willassist in moving the tube inwardly to take up any slight clearancebetween the end of the tube and shoulder 14. After such engagement,fingers 38 will tend to straighten out and dig more tightly into thetube but because the tube is now bottomed against shoulder 14, therewill be resistance to axial movement of the radially inner ends offingers 38 as the nut continues to move axially. Because the ring 36 isvery thin and is flexible, it may bend somewhat as shown in FIG. 2, orit may be scraped inwardly along the tube, depending upon the materialof the tube and its hardness for resisting embedding of the fingers intothe surface of the tube.

Because of the thinness and flexibility of the ring 36, the latter maybend in the manner shown in FIG. 2 with but a small portion of thewrench torque that is required to be exerted upon nut 19 for drivingsleeve 24 to its contracted position. This is important because sleeve24 is relied upon to provide both the main gripping force upon the tubeto retain it in the coupling and for having tight sealing contact withboth the tube and body flare mouth 15. If too much of the wrench torqueis absorbed by ring 36, nut 19 might not be moved sufficiently far ontobody 10 to properly deform sleeve 24 into its gripping and sealingposition. Thus, it is preferable that no more than about one-fourth ofthe wrench torque applied to nut 19 for threading it into its finalposition on body 10 be absorbed in the moving and bending ring 36 sothat at least about three-fourths of such wrench torque is utilized formoving and deforming sleeve 24.

As a practical matter, initial tightening movement of the nut afterinsertion of the tube into the coupling will cause ring 36 to move thetube inwardly for taking up any slight clearance that might existbetween the end of the tube and shoulder 14 before sleeve 24 has beenmoved forwardly a sufficient distance to grip and move the tube. Thus,ring 36 functions to not only initially support the tube in itsapproximately correct position within the coupling but also functions tomove the tube to such correct position before sleeve 24 is deformed intoengagement with the tube so that sleeve 24 in turn will functioncorrectly.

Although the coupling as illustrated in the drawings and thus fardescribed utilizes an external thread upon the body member 10 and aninternal thread in nut 19, it is obvious that these could be reversed sothat the body has an internal thread axially outwardly of flare mouth 15and that nut 19 have an external thread rearwardly of shoulder 20. Also,the threaded connection between the nut and body could be supplanted byflanges on the same and with bolts through the flanges utilized fordrawing the nut and body parts together.

I claim:
 1. A coupling for tubes comprising a body having a bore forreceiving a tube, a nut, adjustable interengaging means on the nut andbody operable for moving the nut toward the body, said nut and body wheninterengaged forming a chamber closed at its axially outward end, adeformable sleeve within said chamber, said nut and sleeve each having abore for receiving the tube, said sleeve being engageable with the nutand body so as to be actuated and deformed thereby into grippingengagement with the tube, and a metal member carried by the nut axiallyoutwardly of said chamber and being operable independently of actuationof the sleeve for engaging and holding the tube within the nut andsleeve prior to actuation and deformation of the sleeve into grippingengagement with the tube, said sleeve providing the main grip upon thetube when deformed by the nut as aforesaid said member being spaced fromsaid sleeve and at all times out of contact therewith.